Circuits for electromagnetic sound reproducers



April 27 1926.l

C. E. BRGHAM ET AL CIRCUITS FOR ELECTRMAGNETIC SOUND REPRODUCERS Filed Nov. 16, 1925 CEC/L E. 5x2/@HAM CHARLES ,a KME INVENToR;

ATTORNEY'.

Patented ipr. 2?, i926.. i

onoiL n. nRIsnz-na ,ann catalanas R. Rows, `or1 EAST ORANGE, NEW JERSEY, .es-` 'siemens To nueivnns LABORATORIES, me.. or NEWARK, NEW JERSEY, A COR- PRATION F NEW JERSEY.

CIRCUITS EGR ELECTROMAGNETC SOUND REPRODUCERS.

application led November 16, 1925. Serial No. 69,386.

To all whom it may concern:

Be it known that we, lucir. E. BiuGHArr and CHARLES R. Rowe, citizens of the United States, residing at East Grange, in the t county of Essex and State of New Jersey,

have invented certain new and useful lmprovements in Circuits for Electromagnetic Sound Reproducers, of which the following is a specification.

Our invention relates broadly to electromagnetic sound reproducers and more particularly to a construction of electromagnetic sound reproducer` forthe efficient reproduction of music an voice frequencies.

One of the objects of our invention is to provide aplurality of magnetic circuitsfo'r a loud speaker or electromagnetic sound rcproducer used in radio reception, each of which may be efficiently responsive to a particular range of frequencies so that the integral edect of all ofthe circuits is the ethcient reproduction'of sound at good tone qualities.

Another object of our invention is to pro- 'vide a. loud speaker having a plurality of branch circuits therein each efliciently responsiveto a particular range of frequencies for the eliicientl reproduction of signaling energy of widely varying frequencies and the stressing of all of the notes of differing tone quality to bring out the various inflections of the sound.

Still another object of our invention is to provide a plurality f circuits in an elcctromagnetic sound reproducer which may be selected for connection in the output circuit of an electron tube amplification Asystem in orderto change the impedances of the-relproducer to match the impedance of tubes of different characteristics.

Our'invention will be more clearly understood fromthe following specification by reference. to the accompanying drawings, wherein: f

Figure 1` isa crosls-sectional view taken through an electromagnetic sound reproducer embodying thc principles of our inventionyFig. 2 illustrates one arrangement of branch circuits' which we may employ in a loud speaker.; Fig. 3 illustrates a.k modified arrangementof branch circuits which comprise the electromagnetic system of the loud speaker ;v Fig. it shows another circuit arrangement for the circuits of a loud speaker unit has a low inductance.

whereby the high and low notes are eiiciently reproduced; Fig. 5 illustrates a construction of switching arrangement for controlling the circuits within the loud speaker; and Figs. 6 and 7 show different arrangements of the loud speaker windings which 00 may be 'secured by manipulation of the switchingarangement of Fig. 5.

Our invention contemplates the connection of a plurality of branch circuits in the outf put ot' an electron tube audio frequency am- 65 plifying system'which comprise the electro.- niagnetic windings which Vactuate the "dia,- phragm of the sound reproducer. We have discovered that soundv of Widely varying frequency may be efficiently reproduced by providing two independent circuits in the electromagnetic sound reproducer, one of which. comprises a low frequency unit and theothel of which forms a high frequency unitv The low frequency unit is arranged to have/a high inductance. while the high frequency The high fref quency unit may be tuned by means of a con" denser interposed in series with the high frequency unit. By the arrangement of the s0 multiple circuits in thev electromagnetic sound reproducer a faithful reprpduction of all of the varying tone frequencies may be secured. Y n

Referring to the drawing in more detail, we have shownin Fig. 1 an electromagnetic sound reproducer emliodying the improvements of our invention. Reference character 1 designates a casing having a downwardly depending annular ring portion 2 90 therein forming a mounting for a sound reproducing diaphragm 8 in the upper portion of the reproducer. An acoustic horn is suitably supported in a ferrule member 3 screw threaded at 4 into the sound rcproducer eas- 95 ing. The interior of the sound reproducer casing 1 is screw threaded at 5 enabling an annular ring member 6 to be adjusted therein for supporting the diaphragm 8 0n an upstanding annular rim 7' carried thereon. 100 The electromagnetic driving mechanism is carried by a rotatable plate member 9 screw threaded into the lower portion of the 'casingl 1 and rotatable'therein under control of a lever 10? A pair of angle pieces 1l com- 105 prising the poles of the electromagnetic sound reproducer are carried by the rotatable plate member 9 by means of terminal members l2 and il. A suitable permanent niagnctif.; system l5 is provided for cooperation n'iih the. pole pieces il. The pole pieces il. are extended vertically to a greater extent than has heretofore been normal in t `rctroniagin';tic sound reproducers and adjcccntthe top of the pole pieces 11 We provide bobbins i6 and l? which are wound li such manner as to provide a circuit resonant 'to the high notes with a condenser 2O in circuit therewith. Below the bohhins comprising the high Jrrequency unit of the receiver n'cprovide magnet bobbins 1S and 19 vwhich comp ise the low frequency unit.. 'The wiri ing 'rangement oi' the sets or" units in the output circuit of an electron tube is more cleaixy illustrated in Fig. 2 ivhcre he units are connected in the plate circuit of an elcciron tube 21 and ui ilized to impress the man'- netic efi'ect thereof upon the diaphragm S. ln `Fig. 3, Wc have shown the sev sets of windings designed for the high and lovv Jfrcpicncy notes' parallel connected in *l fill ine output circuit oit electron tuhc Qi without the inclusion ot a. condenser in series 'with the high frequency Winding.

n i We have shown the sets of Windings connected in series, with the condenser Q0 in series with the hohhins lG-l f ni1'iing the high 'frequency nuit. in Fig. 5 We have shovvn diagrammatically an electromagnetic sound reproducer wherein v[he pole pieces i are wound separately with bobbins i212 and with the terminals thereof brought out to sets of contacts Q7 and QS which may be controlled by snring strip men'ibcrs 9.5 and QG under the action of the push-pull switch to connect the. windings 2:2 and Q3 as represented in Fig. (S, or in parallel as represented in 7 for changing the impedance oi the electromagnetic sound rcproducor to match the impedance of' electron tubes of diii'erent characteristics. vWe may also provide e switching means 'for the arrangement of windings and associated condenser in the assembly illustrated in Fig. l.

It .vili be understood that by the ar ange ment of high and low frequency units, the entire range of audio frequency notes may be reproduced With maximum efiieiency for obtaining perfection in the reproduction ot varying frequencies.

While We have described our invention in certain particular' embodiments, we desire that it be understood that modications may be made and that We intend no limitations upon the invntion other than thos innioscd by the scope of the appended claims.

W'hat we claim and desire to secure by tiers' lfatent of the United States is Ln electromagnetic sound roproducer, ibination er" an electromagnetic er, a diaplnagm actuated ley-said driver, a piurality Aof windings carried by said audio frequency notes, said windings being positioned adjacent each other on seid electromagnetic driver viter combining their edects or ope-ration of said l diaphragm over the entire audible range of voice- Hennen-cies.

2. ln an electromagnetic sound reproducer, 'the combination with a casing, of an electromagnetic driver positioned therein, a diaphragm carried within said casing and arranged to be actuated by said electromagnetic driver, said electromagnetic driver including a plurality of independent windings, each of said windings being eiiicientiy responsive to a elected range of audio frequency notes, wwhereby said electromagnetic driver operates said diaphragm over the, combined range of said audio frequency notes.

3. een electromagnetic sound reproducer comprising in combination a casing, an electromagnetic driver positioned Within said casino', adiaphragm carried Within said casing for actuation by said electromagnetic driver, said electromagnetic driver including pair of pole nieces, each of said polev pieces having a plurality of windings theren, said windings being connected in separate circuit and responsive to different ranges of audio frequency notes, whereby said electromagnetic sound reproducer is efficientlyv responsive over the entire audible ra. ge of frequencies.

an electromagnetic sound reproducer con'iprising in combination a casing, an electromagnetic driver carried Within said casing, diaphragm p sitioned in said casing and actuated by said electromagnetic driver, d electromagnetic driver including a pair o; extended pole pieces, a plurality of Windings carried by said pole pieces, said Windings being separately responsive to pa rticular bands frequencies for operating said electromagnetic driver efficiently over the entire range of audible frequencies. l

An electromagnetic sound reproducer comprising in combination a casing", an electromagnetic driver carried Within said casing, diaphragm positioned in said cas ing and actuated by Said electromagnetic. driver, said eiectromagnetic driver including a pair oi ext-ended pole pieces, a plurality oi? windings carried by said Pole pieces, said windings each having values of 1nductance proportioned to each other` in such manner that a plurality of said windings are eiciently responsive to one band of audio ireqr cies, while others of said 'windings .ciently responsive to another band of i 'frequencies for the eiiicient reproo. in eiectrornag eticseund reproducf-u comprising in conicnnatlon a casing, an elecorion of' sound over the entire audible tiomagnetic driver carried within said casing, a diaphragm positioned in said casin and actuated by said electromagnetic driver, said electromagnetic driver including a pair of extended pole pieces, a plurality of windings carried by said Pole pieces, a condenser arranged within said casing and lhaving a value related to the inductance of one pair of said windings for. the eiicient reproduction of the higher audible notes and another pair of said windings having an inductance value proportioned for the ef ficent reproduction of the lowe r band of audible notes,'wl1ereby all of said windings operate to efficiently reproduce sound' over the entire' range of audible frequencies.

An electromagnetic sound reproducer comprising in combination a casing, an electiomagnetic driver carriedvwithin said casin(Y a dia hra in ositioned in said cas-- I ing and actuated by said electromagnetic driver, said electromagnetic driver including a pair of extended pole pieces, a plural'- ity of pairs of windings carried by said pole pieces, one pair of said 'windings having a value of induc'tance so proportioned that the higher audio frequency notes may be reproduced thereby and another pair of said windings having an inductance of such -value that the lower audio frequency notes may be eiiciently reproduced thereby, with the windings having characteristics for the eflicient reproduction of the higher audio frequency notes positioned adjacent the u per extremities of said pole pieces, while the windings ,proportioned for the eiicient reproduction of the lower audio frequency notes are positioned adjacent the lower porvtions of said pole'pieces in such manner that 'the conjoint action of said windings serves to actua-te said diaphragm over the entire range of audible frequencies.

8. Anelectromagnetic sound 'reproducer comprising in combination a casing, an electromagnetic driver positioned within said casing, a sound reproducing diaphragm carried within said casing and actuated by said' clectromagneticidriver, a pair of pole pieces for said electromagnetic driver, in'-V dependent sets of windings positioned. on

said pole pieces,one set of said windingshaving a low induetance value, whileI the other set of said windings has a high inductance value, with a condenser positioned in series with said rst mentioned set of windings and havin a. value such that a high reactance is o ered for'the range of frequencies for which the other set of windings responds and a relatively low reactanoe for higher audio fre uencies, whereby said diaphragm may be e cientlyroperated over having a low inductance value, while the other set of' said windings has a high inductance value, with a condenser p'ositioned in series with said irst mentioned set of windings and having a value such that ahi li reactance'is offered for the range 'of requencies for which the other set of windings responds and a reiative- 'I ly llow reaetanee for higher"- audio` frequencies, said first mentioned set of windings being positioned on the upper extremities of .said ole pieces adjacent said diephragm, whi e the other set of said windings is positioned adjacent the lower por-' tion of saidpole ieces,whereby said diaphragm may be e ciently operated over the entire audible rance of notes.

.In testimony whereof we ax our signatures.

CECIL E. BRIGHAM. CHARLES R.' ROWE. 

